This invention relates to cast concrete road barrier systems and methods for their placement and use, and more particularly to improved road barrier systems and methods that result in more secure placement of cast barriers, greater visibility of the barriers, increased height by the use of additions thereto, and particular features for particular applications.
Cast concrete barriers, like the barriers 15 of FIG. 1, protecting a work site 17 along traffic lanes 18 of highways and at road edges are well known. These typically have a broad, flat base and taper upwardly to a more narrow top 30" to 40" above the road surface. They may be temporarily or permanently installed. Often, at or near a shoulder, where the thicker lower portion of the barrier tapers to a narrower upper portion, recesses define locations at which vertical openings from the recesses to the supporting bottom surface can receive fasteners extending through the recesses and into the road surface. Surface water creeping under the barriers can reach the fasteners where they emerge from the barrier and enter the road surface. With time this can cause deterioration of the fasteners and significantly affect the strength of the connection.
Trucks with high centers of gravity can impact barriers presently being used and topple over the barriers into a work site or down an embankment. For this reason, standard barrier heights have gradually risen from 32 to 34 and up to 42". Although some provisions have been suggested to address the problem, barriers that rock as illustrated in FIG. 2 when impacted by a vehicle, as indicated by the unnumbered arrow, can expose the facing end surface 19 of the next barrier in a line so that what starts as a glancing blow ends with direct, head-on impact to result in a much more severe accident. Low metal strip barriers and even the cast concrete barriers currently in use between opposing traffic lanes are often unable to protect against the glare of approaching headlights. Particularly on bridges, high barriers block the view and the make drivers and their passengers feel too narrowly enclosed. Lower barriers, on the other hand, can permit vehicles with higher centers of gravity to topple over them, as mentioned.
Along many roads, low metal strip barriers continue to be used rather than being replaced by higher, less easily broken or damaged, and therefore more secure, cast concrete barriers. Uprights in the form of steel I-beams or wooden posts secure these. Because of flexibility of the metal of the barrier strip, a vehicle impacting the strip at the location of the post can sever or knock down that upright.